Outdated LRE docs

[DimitarNestorov]

I was going through the LRE docs and they seem outdated: https://docs.nativelink.com/explanations/lre and https://docs.nativelink.com/rbe/nix-templates#the-lre-template

I tried the first command and it seems like that template is no longer available:

$ nix flake init -t github:TraceMachina/nativelink#lre
error: flake 'github:TraceMachina/nativelink' does not provide attribute 'templates.lre' or 'lre'